Details

First of all, not all plain text-based mimetypes starts with text/:
i.e. application/sql for SQL dumps (already handled in FileExcludeFilters),
or application/postscript for PS images. There are most likely to be more.
Alternative solution would be using QMimeType::inherits instead.

Secondly, not all extractors are bad with large files: for example, if it is
a PS image, then PostScriptDSExtractor still might extract useful information.
Issues are mostly caused by PlainTextExtractor, which generates just too much
terms.